The invention is based on a method and a device for producing bent spring elements.
DE 198 16 609 A1 discloses a method and a device for producing flat-beam wipers for vehicles with bent spring elements, so-called flat beams. Said flat beams form the support element of the wiper blade and preferably have a material thickness which varies over the length. Said flat beams are produced from a tempered spring steel strip which is supplied by two feed rollers, which are arranged in a pair, via guide rollers to a bending unit at a continuous feed rate. The bending unit comprises a cutting unit which serves to cut the individual support elements from one another after they are bent. The continuous feed movement is briefly interrupted during the cutting process.
In the bending unit, the spring steel strip is bent firstly in the one direction by three points of contact and is bent back by a small percentage by a subsequent contact point. The degree of reverse bending which is necessary in order to ensure the dimensional stability of the bent support element is determined empirically. As a mean value, depending on the quality of the spring steel strip, a degree of reverse bending of approximately 10% to 40% of the bending which has previously taken place has proven to be effective. The first two contact points in the feed direction of the bending unit are formed by bending rollers, while the third contact point is a cutting edge which interacts with a cutting blade and cuts the finished support element from the spring steel strip. The bending rollers can be adjusted toward and away from the spring steel strip by actuating motors. A predetermined bending of the spring steel strip is generated corresponding to the position of the bending rollers. Actuating rollers are activated by an electronic control unit as a function of various influential variables in a program-controlled manner.
DE 101 15 047 A1 also disclose a method and a device for producing bent spring strip sections. The device comprises a feed unit which supplies a spring steel strip from a supply roll to a bending unit. Provided between the feed unit and the bending unit is an alignment apparatus. The bending unit comprises three bending rollers and a reverse bending roller, of which one bending roller and the reverse bending roller can be adjusted transversely with respect to the spring steel strip by means of an actuating device. The bending unit is adjoined by a cutting unit which is connected to an NC control unit and cuts the individual spring strip sections from the spring steel strip. During the cutting process, the spring strip feed is briefly stopped.